Electromagnetic device for alternating currents.



G. D. LANNING. ELEGTROMAGNETIG DEVICE FOR ALTERNATING OURRENTS.

APPLICATION FILED AUG. 2, 1910.

1,002,71 2. Patented Sept. 5, 1911.

2 SHEETSSHEET 1.

witnesses I maven/$0 z".- finm a. 16 GhariesBLa uni/n C. D. LANNING.

ELECTROMAGNETIC DEVICE FOR ALTERNATING CURRENTS.

APPLICATION FILED AUG. 2, 1910.

2 SHBETSSHBET 2.

WW Q fg www' L aalahs To all whom it mag concern:

CHABLES D. LANNING, OF BOSTON, JVIASSACHUSETTS.

ELECTROMAGNETIC DEVICE FOR ALTERNAT ING CURRENTS.

Specification of Letters Patent.

' Patented Sept. 5, 191.1.

- Application filed August 2, 1910. Serial no. 575,051.

Be it known that I, CHARLES D, LANNING, a citizen of the United States,and a resident of Boston, in the county of Suffolk, State ofMassachusetts, have invented an Improvement in Electromagnetic Devicesfor Alternating Currents, of which the following description, inconnection with the accompanying drawings, is a specification, likeletters on the drawings representing like parts.

This invention relates to electro-magnetic devices, more particularly tothose intended to be energized by alternating currents, and hasparticular reference to improvements in the efliciency ofelectro-magnets which are energized by alternating currents, andparticularly those of relatively slight strength andhigh frequency,such, for example, as telephonic .currents or the like.

My invention will be best understood by reference to the followingdescription when taken in connection with the accompanying illustrationof one specific embodiment thereof, while its scope will be moreparticularly pointed out in the appended claims.

In the drawings: diagrammatically a circuit arrangement, embodying oneform of my invention; Fig. 2 is a plan view of a switch which may beemployed in the arrangement shown in" Fig. 1; Fig. 3 is a centralsection in elevation, partially broken away, and on an enlargedscale,'showing the construction of the switch disclosed in Fig. 2; andFig. 4 is a detail of the connection between the switch arm and itscontrolling spring.

Referring to Fig. 1 of the drawings, I have there illustrated one formof'my in vention applied to a telephone system, and to'an instance whereit is necessary to control a switch or other device by means of a magnetenergized by the voice-caused alternating currents on the telephoneline. In this particular instance the telephone circuit is provided witha repeating station having circuit-changing means for establishingrepeating relations between the sending and receiving station, suchcircuitchanging means being controlled by a voice energizedelectro-magnet.

Referring to the diagrammatic showing in Fig. 1, there is convenientlyrepresented at 1 a telephone station which may be adapted both for thetransmission and the receipt Figure 1 represents of telephonic currents,such station being connected with the repeating station by the linecircuits 2 and 3. The line 2 is split into two branches 4.- and 5, theformer passing through the primary of the transmitting induction coil(3, and thence through the primary of the switch controlling inductioncoil 7 to the switch contact 8. The latter is normally engaged bythepivotally mounted switch 9, the latter being maintained iIl suchposition by the spring or other restoring member 10. The other branch 5'of the circuit 2 forms a receiving'circuit leading to the secondary ofthe receiving coil 11, and thence to the normally opened switch-comtrolled contact 12 at the switch 9. The opposite side 8 of thetransmitting circuit is permanently connected to the controlling switch9 by any suitable means as, for eX-. ample, through the restoring spring10. \Vhile the switch 9 normally engages the contact 8, it may bewithdrawn therefrom and moved to engage the contact 12 on energizatio-nof the switch-controlling electromagnet 13.

Referring now to the sending and receivin station 14: at the oppositeend of the line, the main circuits 15 and 16 lead to the repeatingstation and have connections corresponding generally to those alreadydescribed, which it will not be necessary again to enumerate, therebeing provided, howover, for these circuits a controlling switch 17similar to the switch 9, switch contacts 18 and 19, a switch-operatingmagnet 20 and a restoring spring 21. y i

It will be seen that in the normal state of the apparatus, with themagnets deenergized, the connections remain as shown in the diagram; Inthe arrangement shown I rely upon the initially transmitted voicecausedtelephone-currents to energize the proper magnet and throw the switch tomake the requisite repeating connections. To energize the proper magnet,each magn'lat is connected in series with the secondary of itsswitch-controlling induction coil, and, to secure the best results, Ihave made special provision for rectifying the alternating currentswhich pass from the coil to the magnet, thereby providing auni-directional magnetizing current. To this end the magnetwinding 22has interposed between it and the induction coil a suitable rectifyingelement, such as an asymmetrical cell 23,

the well-known property of which is to tional character.

- also connected prevent the current from passing in one di;

rection while permittingit to passin the opposite direction. Suchasymmetrical element may be provided in any desired-form,

as, for example, in the form of a cell having lead'and aluminumelectrodes immersed in an alkaline electrolyte such as a sodium'ortho-phosphate solution. Such an asyinmetrical cell when placed in analternating current circuit odors very, little resistance when thecurrent passes in at the lead electrode and out at the aluminumelectrode, but when-the current is reversed it meets with a heavyresistance due to a thin filma separate branch circuit from the winding22 and having serially related there- 'to another asymmetrical element,such as the asymmetrical cell 25. The two magnet win'dings' 22 and 24are so connected through their respective asymmetrical elements to theterminals of the induction coil secondary that they tend to reinforceeach "the other,and establish each a magnetic field of the samepolarity. It therefore follows that, in-eaeh alternating current cycle,

the cessation of the decreasing magnetizing current in one circuit isimmediately succeeded by the flow of an increasing magnet- 12mg currentin the other circuit, having the same direction and magnetizing effect.

This not only provides against reversal in the magnet current butactually leaves no interval. of demagnetization, for, at the neutralpoint, a. when theoretically, between the two pulsations there is nocurrent, the'magnet still tends to attract the switch through theresidual or remainant magnetism;

Turning again to the curcuit connections in Fig. 1', the effectof'throwing the switch 17, by means of the voice currents'transmittedfrom the station 1, is'to interruptthe transmitting circuit from thestation 14,

through the branches 26 and 27,- at the contact 1 8 and to complete thereceiving circuit passing thereto through the branches 28 and 29. Undersuch conditions the voice currents generated. at the station 1 arereproduced in the receiving circuit of the station 14 through theinterposition of suitable repeating devices. For this purpose, there isinterposed between the primary of the transformer 6, which is in thebranch 4 of i the main line circuit 2, and the secondary of thetransformer 30, which is in the receiving branch 28 of the main linecircuit 15, a repeater 31 which I have shown in' conventionaldiagrammatic form, but which may be of any design. or constructionadapted to reproduce accurately, and preferably with increasedintensity, the electrical undulations of the circuit 2'3, again in thesecondary of the transformer 30. This repeater herein shown consists ofa magnet coil in circuit with the secondary of the transformer 6 andhaving an armature adapted to vary the pressure in a suitable form ofcarbon or microphonic contact,

thereby varying the current flowing in the primary of the transformer30. lVith the switch l7, 'therefore,'in the dotted line position shown,undulations in the circuit 2-3 are thus reproduced in the secondary ofthe transformer 80 and transmitted to the main line circuit through thebranch or receiving circuits 28, 29, and thus to the distant.sta-

tion. At the same time the transmitting circuit on the lines 2627 beingopen at the switch, the associatedtransmitting apparatus for station 14is, therefore, unali'ected by any energy subsequently transmitted overth'eline 23 from the station. As soon as transmission of voice energyfrom the'station 1 ceases, the magnet 20, being thereupon .deenergized,the switch 17 is restored by the spring 21 to the position shown in fulllines, breaking'from the receiving branch 28 for the station ii andagain completing the circuit for the transmitting branches 26, 27thereof, leaving the repeater in condition again to pass under thecontrol of the next voice currents to pass over the line. Ifvoice energyis transmitted from the station 14 to the station 1 the transmittingbranch for the station 1 is immediately broken by the movement of theswitch 9, which at the same time completes the receiving branch thereofand the voice energy from the line 15, 16 is reproduced withintensification in the line circuit 23, through the. repeater 32, all ofwhich will be readily understood from the. foregoing description. Thecir-' cuit control is, therefore, automatically effected by thetelephone currents themselves, the switch corresponding to that terminalstation toward which. the voice energy is transmitted, being instantlythrown, through the medium of its controlling electro-magnet. to breakits transmitting circuit and place its receiving circuit in condition toreceive and pass on the voice-actuated currents.

It will be observed that the asymmetrical cells 23 and 25 are not in themain telephonic circuit but that the circuit containing the same isinductionally related to the main line clrcuit so that the telcphonlccurrents do not actually pass through these cells and the maintelepl'ionic line circuit cannot be ati'ccted by any variations inresistance of th A asyunnetrical elements.

In the control of a switch, such as described, by means of anelcctro-magnet energized through alternating currents, as, for example,telephone currents, it is ordinarily necessary to provide a spring orother restoring member, having a low rate of vibration which, in thecase oftelephone currents, should be less than the lowest audible toneof the human voice. Otherwise the reversal in the magnetizingcurrent ofthe magnet will", at the zero point of magnetism, tend to release theswitch and allow the spring to restore the same to its normal position,so that the alternations o't'current willv tend to induce a sympatheticvibration in the spring instead of holding the switch steadily attractedduring the alternating passage of the current through the magneticcoils. in a magnet wound and energized as dcscribec, however, theprecaution of an abnormally low period of vibration for the spring isunnecessary, since the switch will remain attracted by the magnet solong as the restoring force of the spring is than the remainantmagnetismwhich is effective be tween the succeeding uni-directional pulsations.Furthermore, since there is no reversal of the magnetizing current, amore effective magnetism 1s secured 'lrom a given strength ofalternating current, which is particularly advantageous in the case oftelephone currents and other weak currents, partlcularly those of hlghperiodicity where self-induction and hysteresisflosscs are apt to begreat.

In Figs. 2 to 4: I have illustrated the-details of a'controlling switchwhich may be employed in connection with a system like I that describedin Fig. 1. Referring to the drawings, the switch parts are mounted upona base 45 of insulating material. The switch arm 46 is a small piece ofsome light conductive material, preferably aluminum, which is showndrilled out further to lighten the same. The switch arm is delicatelyand sensitively supported by a pivoted pin 4t? mounted in jeweled cupbearings 48, so that may execute the slight movement necessary with aminimum amount of friction.

and inertia. The upper bearing is shown ad prstable by means of a thumbscrew 49 and dock nut 50. The switch controlling magnet 51 is suitablysupported upon ahase to face a thin, light armature 52, preferably apiece of soft. thin-sheet iron secured to the end of the switch arm. Thedouble or parallel windings of the magnetic coils are connected to theterminal binding posts 54, 55 and 5t) and are mounted upon the ends ofthe horse shoe core 57 as close t0 the armature as possible. The core 57is preferably of posts soft laminated iron. The .stationary contacts areshown in the form of adjustable screws 58 and 59 adjustably mounted inposts 60 and 61 and preferably tipped with platinum ends which cooperatewith platinum contacts 62 upon the switch arm. The and 61 are connected,respectively, to terminal posts 63 and 64. The switch arm l6 is normallyheld in contact wit one of the contact screws (with screw 09 in Fig. 2)by means of a resilient restoring member, the same herein comprising arelatively long, fine, flexible wire 65 having one end resting in theV-shaped groove of an upturned ear 66 (see Fig. 4:) on the rear end ofthe switch arm, and the opposite end held fixed in a block G'Tfwhich maybe slightly adjusted transverse the axis of the wire in the fixed frame68 by means of tlie fine differential adjpsting. screw 69. The'wire 65is preferably of iridium-platinum and so finely dimensioned asto exert avery deli cate restoring tendency upon the switch 'arm. (*onnections maybe made to the switch arm through the platinum wire 65, thesliding block67 and frame 68 by means of the lead wire 70 and the binding post- 71.iBy adjusting the block (37, the restoring tendency of the spring may beadjusted.

To obtain the-best results and maintain the switch in perfectbalance,the base 45 is provided with the leveling screws 72 and the spirit level7 3.

It will be understood that my invention is not limited to the particulardetails" herein shown, either of construction, circuit arrangement orapplication of the invention, these being submitted for purposes ofillustration only, but that extensive deviations maybe made therefromwithout deperating from the spirit of the invention.

Having thus described my invention,what I claim is:

'1. In a telephone relay system a. two-way repeating device comprisingone or more repeating instruments, circuit controlling means forestablishing and maintaining the circuits to and fromthe repeatingdevice according to the direction of sound trans mission from thespeaking to the listening station, an electro-magnet for actuating saidcircuit controlling means, said electro-magnet being energized throughthe voice caused currents from the speaking station, and currentrectifying means for providing a uni-directional current for the saidmagnet.

, 2. In a telephone relay system a two-way repeating device and a linecircuit leading from each station thereto, said repeating deviceincluding a circuit-changing device for placing either station insuitable repeating communication with the otheraccording to thedirection of sound transmis sion, an electro-magnet actuated by thelOt - c" 'pies of this patent may be'obtaincdfor voice currents ineither'line circuit for op erating said circuit-changing device,parallel windings for said magnet, and an asymmetrical elementassociated with each Winding for causing-current impulses alternatelythrough the two windings having a-uni-dircctional magnetizing effect.

3. In a telephone relay system, a repeating station; terminal stationshaving line circuits leading to said repeating station; a transmitting.circuit and receiving circuit for each line circuit at said repeatingstation; and means for automatically breaking the receiving circuit fromone stat-ion and making the corresponding transmitting circuit on thepassage of voice currents from the opposite terminal station, said meanscomprising an electro-magnetic device energized'by the said voicecurrents; and currentrectifyingmeans for. providing thercfor from thesaid voice currents, a uni-directional magnetizing current.

telephone apparatus of the class de scribed having means for reproducingtelephonicspe'ech, sounds or the like alternately from one main linecircuit into another main line circuit consisting of a telephonetransmitter lndu'ctlon coll, a source of elcctro-motive. force andcircuit connections, electromagnetic apparatus rcsponsive to the voice Icaused currents originated at'either sending LANNING.

five cents each, by addressing the Commissioner of latents. Washington,D. C.

